Automatic telegraph switching system



SePt- 5, 1950 w. B. BLANToN ETAL AUTOMATIC TELEGRAPH SWITCHING SYSTEM 5 Sheets-Sheet l Filed June 20, 1946 Spt. 5, 1950 wl. B. BLAN'roN ETAL 2,520,903

AUTOMATIC TELEGRAPH swTTcHTNG SYSTEM -Filed June 20, 1946 5 Sheets-Sheet 2 Sept. 5, v1950 w. B. BLANTON ErAL 2,520,903

AUTOMATIC TELEGRAPH SWITCHING SYSTEM I. INVENTORS W. B. BLANTON BY R. C. AYERS ATTORNEY Filed June 20, 1946 TO FIG. 4-

w. B. BLANTON ErAl.

AUTOMATIC TELEGRAPH swI'rcHING SYSTEM l5 sheets-sheet 5 sept. 5, 195o 2 52o 903 sPEcmL cLos'ED FIG. 5

FIG. 6

F|G.2 FIG.3 F|G.4

INVENTORS W. B. BLANTON BY Rc. AYERS ATTORNEY Patented Sept. 5, 1950 UNITED STATES PATENT OFFICE AUTOMATIC TELEGRAPH SWITCHING SYSTEM Application dune 2li, i946, Serial No. 677,964

(Cl. l78--3) 8 Claims.

rlhis invention relates primarily to telegraph switching systems and, more particularly, to reperforator switching systems wherein telegraph messages received, or originating at, a switching cent-er are stored in a perforated tape incident to the relaying and subsequent retransmission thereof to a selected outgoing circuit.

The invention is hereinafter described as being applied to what is known as a double reperforation switching system, wherein each receiving circuit at a switching center terminates in and controls a so-called receiving reperforator which perforates a paper tape in accordance with received signals whereby tho signals are stored a first time. Each such reperforator has individually associated therewith a tape transmitter which is operative to transmit code signals representative of those stored in its associated paper tape. By means of plugs and jacks in prior art systems, the sending circuit of such transmitters are extended to selected ones of a plurality of so-called sending position circuits where these signals operate another reperforator, ycalled an intra-cnice or sending position reperforator, whereby the signals are again stored in a paper tape adapted to control a second or sending position transmitter for transmitting such signals to the sending circuit. Patent No. 2,279,295, granted to W. B. Blanton, .April 14, 1942, describes a system of this type in detail and reference is made to this patent `for a description of certain details of the system disclosed herein.

Although the present invention is hereinafter described as being applied to a system such as that described .in the Blanton patent wherein a double reperforation system is shown, it will be apparent that the present invention is not limited in application to this particular system or this particular type of system but that the principles of the .present invention may be applied to various other types of telegraph exchange systems, such as, for example, those wherein single storage is employed. in a single storage exchange system, the transmitter associated with the reperforator terminating a receiving circuit is adapted to transmit directly to asending circuit.

In the present invention, the selection of a desired sending position circuit is 'eiiected automatically under the lcontrol of a directing signal perforated in the tape preceding a message, rather than by means of plugs and jacks as is the case in the above-mentioned Blanton patent.

One or the main objects and features of the invention is to provide a semi-automatic telegraph switching system more eicient in operation in that it requires a minimum of lan attendants time and effort incident to the relaying of a message through a switching center but which is at all time under full control of the attend-ant.

Another obj-ect of the invention resides in the provision of a syste-m which is semi-automatic in operation wherein the selection of an outgoing circuit is effected under the control of directing signals preceding each message and the initiation of the switching of messages is controlled manually. In this connection, another feature of the invention resides in the provision of means for switching one message at a time from an intra-cnice circuit to the automatically selected sending position circuit in response to the individual actuations of a manually operable element and in automatically switching all messages that may be stored in a tape to their respective sending position circuits, incident to a single actuation of another manually operable element.

Still another feature of the invention resides in the provision of means for manually controlling the selection of the desired outgoing circuit in the event of the absence oi a directing character or group of characters preceding a message which is to be switched.

Still another feature of the invention resides in the provision of means whereby the directing character preceding a message may or may not be deleted from the message as it is relayed through the switching center.

rlhe above and further features and objects of the invention will be more apparent hereafter in the accompanying detailed description and drawings, in the latter of which- Figs. l, 2 and 3 together represent diagrammatically an intra-cnice circuit;

Figs. 4 and 5 together represent diagrammatically a sending position circuit; and

Fig. 6 illustrates the manner in which Figs. 1 to 5 may iit together to form a complete circuit.

rhe intra-office circuit oi Figs. 1, 2 and 3 includes a tape transmitter Il adapted to operate under the control of a perforated tape l2. The tape l2 is prepared, in the embodiment of the invention shown, by a reperforator i3 controlled by signals received over a receiving circuit R. However, the perforating tape l 2 could as well be prepared by an operator at a local sending position at the switching center in which case a keyboard perforator would be substituted for the reperforator I3.

If it is assumed that the tape l2 between the reperorator i 3 and transmitter l l has no message stored therein and contains nothing but blanks, which is the perforation sometimes employed in the present system to separate the messages and enables the last message character in the tape to reach the sensing pins of the transmitter, the tongues of the transmitter will be in contact with their spacing stops. These tongues are connected by individual conductors through tongues and back contacts of a relay l2! and a cable I4 through the coils of respective so-called pulse relays I5a to 55e to potential. With a blank in the tape over the pins of the transmitter, relays I5a to Ie will all be deenergized to complete aV circuit from ground through back contacts and tongues of line switching relays it, IT, I8, and I9, and pulse relays le, l5cZ,I5c, |55, and |5a, and the coils of relays 2| and 22 to potential. Accordingly, relays 2| and 22 will be energized for the assumed condition.

VWhen the perforator i3 begins to store a message in the tape I2, the extra supply of tape Will permit the tape lever contacts 23 to close whereupon a circuit frompotential through the coil of the step magnet SM of the tape transmitter II, the lower contacts 2d of a key switch 26, tape lever contacts 23, the back Contact and left-hand tongue of relay 2, the outer left-hand tongue and back contact of relay 8|, the make contact and inner tongue of relay 22 and a pulse generator 28 to ground. Pulses from the generator 28 areY thereby effective to periodically energize step magnet SM of the tape transmitter lwhereby the tape l2 is advanced one step for each energization thereof and as long as blanks appear over the sensing pins of theA transmitter and contacts 23 remain closed the above tape stepping circuit is maintained. However, when the irst character of a message appears over the sensing pins which in this case will be the message directn ing character, one or more of the relays ld to |56 will be energized to interrupt the circuit to the relay 22 whereupon the said relay will release and interrupt the described circuit to the step magnet SM. l

In the following description of the intra-cnice circuit, the above-mentioned relays |2I and 3|, together with hereinafter-mentioned relays l5, 82,122 and |523 operate in substantially the same manner and are for the same purposes as relays having these same reference numerals in Fig. 2 of the above-mentioned Blanton patent.

Some of the tongues oi the relays ld to |56 are arranged in a fan circuit in such a manner that various circuit paths, one at a time, are

`completed therethrough when ythe relays are operated in different combinations. Four such circuit paths are shown in the drawings extending to four conductors 3|, 32, 33 and 34. Each of the conductors Sito Sil extend one of the circuit paths established by the fan circuit through a back contact and tongue of three of the relays I6 to i9 and through the coil of the other one of the relays i6 to I@ in series with a corresponding coil of relays 56a to I da to potential. Thus when a circuit path is completed through the fan circuit to any oneY of the conductors 3| to 3, the circuit will be extended through the coils of one of the pairs of relays to potential provided each of the other relays of the set i5 to I9 are deenergized. For example, should the relays lea to |56 be operated in such a combination as to establish a circuit path through the ian circuit thereof to conductor 33, relay pair Il and Ha will be conditioned for operation provided relays I6, I8 and I9 are deenergized.

In addition to the functions set forth above Ywhich include the partial establishment of a circuit for operating one of the pairs of relays It to i9 and lilo to lila, the operation of one or more o1" the relays ld to |56 establishes a circuit for the operation of a socalled Connection Request lamp St to inform the attendant that the message or at least the nrst part thereof Y has appeared in the storage tape E2. rlhe circuit to the Connection Request lamp 35 may be traced from potential through the lamp, a iront contact and tongue of an operated one of the pulse relays Ilia to 59 and a back contact and tongue of all relays l5@ to |59 below the operated one, through the four tongues and baci: contacts of relays IES to ill in series to ground.

rlhe attendant upon seeing the lamp .iii illuminated may then operate the Single Message start key 3l' to apply a ground to the circuit established through the coils oi relays Il and Ila and including conductor 33 and contacts 'of relays |511 to I 5e operated in accordance with the directing character preceding the message. The ground applied to the above circuit extends through hack contacts and tongues of relays 2| and 38 and originates at the hack contact and tongue oi a disconnect relay 3Q. The above circuit ior operating relays il' and lla is not completed until the slow-to-release relay 2| has released, which insures that the tongues of the relays ld to ie will have settled down and thus eliminate the possibility of a false selection. When one of the line relays, such as il, operates, it and its companion one of a pair which in this case will be relay llc, lock up from the ground at the disconnect relay 39 through the front contact and outer tongue of the operated line switching relay, such as El, independently of the key 3l and contacts Yof relays ld to |53, 2| and 33.

The operation of one of the line switching relays, such as relay Iia, completes a circuit from ground through the front contact and outer tongue thereof to conductor l and thence through a tongue and back contact of relay 112, the righ"hand tongue and back contact of relay 38, a switch d3 and the coil of the step magnet SM of the tape transmitter II to potential. If the switch t3 is closed at this time, the grounding of the above circuit by the operation'of relay Ila will eiTect energization of the step magnet SM. As will be described hereinafter, the operation of relay 8| just prior to the transmission of the message will cause relay 38 to operate. The inner right-hand contacts of relay 3S will open the circuit to the step magnet SM and cause the directing character over the pins of the tape transmitter to be stepped out of association therewith. Such operation of the step magnet SM of the transmitter H occurs before the transmitter starts transmitting to the sending circuit and hence the directing character will not be transmitted to the sending circuit. However, if the operating procedure is such and the 4particular sending circuit to which the messages are to be relayed have further use for the directing lcharacter of the message in the tape, the switch is may be opened or left open and consequently the operation of any one of the relays, such as la to |9a will not eiiect advancement of the -tape and the tape transmitter il as is the case with switch Q3 closed. y

In addition to the above, the operation of one of the relays, such as lla, extends the nine conductors of cable @il to cable l. The nine conductors of cable lill are multiplied to the nine inner tongues of all the relays l6 to I9a andthe ninel conductors of cable 46 are multiplied to corresponding contacts of oneofthe relays, such as Ila, ofall the intra-office circuits included in the system. With` respect to the nine conductors of cables 44 and l46, the operation of the relays, such asllc, corresponds to the insertion of the. plug P, Fig. 2 of the aboven ientioned Blanton patent-into a jack., such as l 4.l f

The No. 6. conductor of cable` 46 terminates in positive potential andthe operation of relay4 Ha completes a circuit :froml this positive` potential to a control grid of a vacuum tube .41,causing said vacuum tube topasscurrentand effect energization of relay 16 in the plate circuit thereof. Concomitantly the operation of relay Ila completes a circuit from negative. potentialthrough a. resistance 48 andthe ninth conductor of cables 46 and-44,the left-hand coil of arelay49,back contacts and tongues -of relays 22 and 82 to a front contact of relay 16, the associatedtongue of which isconnected through an allotter 5l to ground. The allotter 5l is common to all the inl tra-office circuits of the system and sequentially applies ground to the right-hand tongues of re lays 16vof these circuitsto cause operation of re. lay 49 if the sending position circuit isidlev at the time of operation of a line relay, such as lla. Relay 49 in operating through its inner left-hand tongue places a ground on the-No.. 9 conductor of cable 46 and thus prevents the operation of r-elay 49 ofA any other intra-,cnice circuit, and hence another intra-oiiice circuit cannot' be lconnected toa lousy sending position circuit. However, thefoperation of a relay T6- through. its preliminarymake contacts of the inner right hand tongue registers a connection, and on the release of the sending position. circuitby the connected intrafoffice circuit, al second intra-offrce circuit having an operated relay 'i6 will be automatically connected thereto.

The operation of relay 16, as above described, through an obvious Ycircuit including `a tongue of front con-tact thereof and aY tongue and back contact of relay ill' and 82 efEects illumination of the Standbyv lamp 52 and when relay 49 operates, it locks up through a circuit including .its right-handcoil and contacts 53 of relay 82.

Asrelay 49 operates, it `co-nflpletes a circuit from' positive potential through the front contact and outer left-hand tongue thereof, contacts 54 associated-with `the secondright-hand tongue of relay 82, the coil of relay 8l., the eighth conductor of cable 44, a tongue and front contact of relay lla, the eighth conductor of calolel 4:6,fthe coil of relay 56,` back contacts and tongues of relays 5"` and 58, a front. tongue of a normally operated relay 59, the lower contacts 6|v ofa close-out switch 62 and a tongue and back contact'of a relay-63 to negativepotentiah This circuit effects. oper tion of relays 8l and 56 and the former in operating removes the ground from the circuit tothe Standby lamp 52 whereby the said l'ampceases to be illuminated and indicates that `a connection has Vbeen made from the yintra-milice circuit to a sending position circuit. Also, the operation of relay 8l, which is sometimes referred. to as the seizefrelay, through:v its outer right-hand tongue completes a circuit -for operating relay 38 and prepares a locking circuit for holding relays l2! and I 22 operatedwhen a circuit is completed thereto in the manner set forth hereinafter. 1n addition to the above, the operation of relay 8l prepares a circuit` for the operation of the step magnet SM of the tape transmitter H. Relay 59 held Aoperated by. plate current flowingl through vacuum tube which is controlled by a conden-l ser resistance ktiming circuit 60A in conjunction with contacts 60B operated by a tape reel'cam 66C. The tape reel cam 60C is rotated'by advancement of the paper tape 18 through the. reperforator l2 and as long as they tape feeds properly vacuum tube 6U passes plate currentfto'maintain relay.59 operated. However, should the tapev ofthe reper'forator be tied up vor fail to feedproporly the tap@` tie-up control circuit eiiects'releas'e of relay 59 to interrupt the circuits controlled 'by the energization thereof and effects `illumination of the tape tie-up illuminating IampSIJD., The: operation of the tape tie-up reset button'65 after remedying .a tape tie-up condition restoresv the tape tie-up circuit to its normal condition.

. As relay -5t of the sending position circuit, shown in Figs. 4 Vand 5x operates it performs the following functions: (l) establishes 'a vholding circuit for itself and relay 6| which is independ ent of contacts of relays 51, 58 and 59 and 'contacts 6l `of the "close-out key 62; (2) removes negative potential at its second right-hand tongue from the circuit leading tothe coil of relayy 5-8 so that. this relay cannot be operatedY While" the sending position circuit is busy orwhile'itis seized by. anintraeoflicecircuit; (3) com'pletesa circuit for the operation ofrelay 5T; (4) prepares, through. its outer right-hand tongue, a circuitffor theoperationof a transfer relay which attliisy time will be open at switch contacts 64 included inthe numbering machine 66;' (5)'r through its' third vright-hand Atongue and front 'contact -ap-A- plies ground to a circuit including a. tongue and back contact of relay G5 and the coil of relay 6T to potential ,whereby relay (il` is operated; (6l completes a circuit from negative potentialI through the coil of operating magnet 6'8 'of'fthe numbering machine E6', the nfthright-hand tongue. and front contact of relay 56,' the hack contact and outer tongue of relay 55,' the 'front cuit reperforator 'i2 and individual coilsfof reald' ing relays T3', 'M and T5, in the manner shown, to the ve inner tongues of relay 65.. The correls-pondingback contacts of relay 65 extend'to operating contacts of the numbering machine '66 which in the manner well known in the art are operated for a predetermined numberv of `operations to represent the signals' which it'is'desired' to perforate in the tape of the sending position circuitreperforator' 'l2' ahead of the message'to'be stored therein. The signals or code groups-transmitted from thenuinberi'ng 'machine G6 normally include signals` representing consecutive'nurnerals along with other circuit identifying signals. They rerforator 'V2 in the preferredVeIn-bodiment includes 'atape feed-out mechanism of the type well' known in the artl andsuch a mechanism is indicated generally by' reference numerals 10". Thetape feed-out mechanism 16* may operate to feed out a predeterminedy length 'of' tape on the cessation of signals and a taut tape condition to permit the last perforated signal character inthe `relay |2| operates. establishes an obvious circuit through th-e coil of tape to reach the transmitter or the tape feed-out mechanism may be initiated into operation at other times such as at the end of a vmessagev to permit the last message character to meet the transmitter.

When the numbering machine 66 completes its sequence of operation, contacts 64 thereof close and complete a circuit through the outer tongue and front contact of relay 56 and the coil of relay 65to potential, whereby relay 65 operates. Relay 65 in operating transfers the circuits to the selecting magnets 1|' of the reperforator 12 to five conductors of cable 46 which extend through front contacts and tongues of relay |1a and cable 44 to front contacts of the rst ve left-hand tongues of relay 12|. Relay |2| is, at this time, deenergized.

In addition to the above, the operation of relay 65 by its outer tongue interrupts the operating circuit from the No. 6 contacts of the impulse unit 69 to the operating magnet 68 of the numbering machine 65 and transfers this circuit through a front contact of relay 65, the coil of relay 10, the seventh conductor of cable 46, a front contact and tongue of relay |1a, the seventh conductor of cable 44, the front contact and inner right-hand tongue of relay 8|, the outer right-hand tongue and back contact of relay |2| and the right-hand coil of relay |22 to potential. This causes energization of relay |22 which is a pulse absorbing relay, and the operation thereof extends the above circuit through the left-hand coil of relay |22, the coil of relay |2 a back contact and tongue of relay 21, the front contact and outer right-hand tongue of relay 8| to Y ground. There is no current through the coil cf relay |'2| or the left-hand coil of relay |22 while the No. 6 contacts are closed as these contacts short-circuit these two windings. When the N o.V 6 contacts open, the short-circuit is removedand Operation of relay |22 also relay 82 which becomes energized and locks upv from ground through a tongue and front contact of relay 16. A

; As'relay l2! operates, it switches the rive conductors of cable M to the five tongues of the tape transmitter and this occurs at the proper time to cause the perforation inthe tape |2 over the pins of the transmitter to be transmitted to the reperforator 12 on the following closure of the first ve contacts of the impulse'unit y69. By its'outer right-hand tongue, relay |2| transfers the circuit which'effe'cted operation of relay |22 through the coil or relay 85 to the point 11 where the ycurrent divides; half going through the righthand coil of relay |23 to the step magnet SM of thetape transmitter and the other half going through the left-hand coil of relay |23, a front contact and tongue of relay y8|, a tongue and back contact'of relay 21, the tape lever contacts 23 the contacts 24 of key switch 26 to the step magnet. Thus for each subsequent closure of the No. contacts of the impulse unit 69 an operating pulse is provided for the step magnet SM of the transmitter Il to advance the tape therein in conjunction with the closure of the first five contacts of the impulse unit to cause `the characters in the tape l2 of transmitter to be reperforated in the tape 18 issuing from the reperforator 12. 'Ihis circuit to the step magnet SM is maintained as long as the tape lever contacts v23 remained closed and the relay 21 remains deenergized. Relay 21 is operated when atapetiefup4 atthe reperforator 12 occurs. Thus,A

8 a message appearing in thetape V|2"isv relayed through the intra-cnice circuit of Figs. 1, 2 and 3 to a reperforator 12 in therdesired'sending position circuit, Figs. 4 and 5, and isy reperforated in the tape 18 thereat. The tape 18 in the manner well known controls the operation of a vdistributor transmitter 19 operative to transmit signals stored in the tape 18 to a sending line L.

The messages in the tape' l2 are separated by end-of-message signals and the transmission of such a signal from the transmitter I is effective to stop operation thereof sovthat the transmitting circuit from the tape transmitter may be switched to the same or another sending position circuit depending upon the destination of the following message. In the embodiment of the invention disclosed the end-of-message signal consists of a' double period and these combinations like all other characters of the message transmitted from the transmitter cause some or all of relays 13, 14 and 15 to be operated in accordance therewith. When a period is sent from the transmitter only relay 15 of the above three operate and it, through a front contact thereof, applies a ground through contacts of relays 13 and 14, a back contact of relay 86 through the coil of a relay 81 to potential. This iirst period, therefore, eiects energization of relay 31 and as relay 15 releases, relay 86 operates to transfer the circuit which operated relay 81 to relay 88. If the next succeeding character is also a pericd,-the second operation of relay 15 Vwill effect operation of Vrelay 88 and as'relay 15 releases a second time, relay 63 operates. The operation of relays 53, 86, I81 and '88 in the above manner in response to an end-of-message signal is similar to the operation of corresponding relays in the above-mentioned Blanton patent. The operation of relay 63 is timed by the opera-Y tion of the No. 8 set of contacts of the impulse unit 69, and the interpcsition of any character other than a blank between the two periods of the end-of-message signal through an obvious circuit effects energization of relay B9, whereby the holding circuit to relays y8b and 61 whichkoperated in response to the rst period is interrupted.

The operation of relay 63 in response to the end-of-message signal, through its inner righthand tongue, removes the holding ground applied through a tongue and front Contact Aof relay 65, a tongue and` front contact of relay 56 to the coil of relay i| whereupon relay 65 releases. Also, operation of relay 63 through its outerA righthand tongue removes the negative potential from the circuit extending through the coils of relay 56 and 8| whereupon these relays also release. Release of relay 65 disconnects'the transmitter from the sending reperforator 12 of the sending position circuit, while release of relay 8| efiects energization of the disconnect relay 39 and the release of various other'relays of the intraoiiice circuit.

As relay 39 operates it removes ground from the circuit holding relays Yl1 `and Ha -operated whereupon the said relays release. The release of relay lla is the equivalent of withdrawing the plug from a jack in the above-mentioned Blanton patent While relay l1 in releasing restores the circuits Vthrough back contacts and tongues thereof to normal. If the perforation over the pins of the transmitter is at this time-a blank, relays ld to |5e will be deenergized and the circuit through the coils of relays 2| and 22 Will be reestablished Vto cause the blank Vcharactersin the tape l2 to be idled through the tape trans- Initter Il. The idling of the blanks through the transmitters continues until the tape lever contacts 23 open or the directing character preceding the following message is advanced over the pins of the transmitter, When the directing character of the succeeding message is stepped over the pins of the transmitter, it eiects another operation of relays ld, to 85e in the manner described to prepare a circuit for operation of one of the pairs of line selecting relays le to I9 and i'a to i911. Thereupon the operator may depress the key `3l to initiate transmission oi this succeeding message to the proper sending position circuit.

It often happens that a plurality or" messages will appear in the tape l2 and that it will be desirous to switch these messages to their proper sending position circuits automatically without the necessity of the operator actuating the key 3l to initiate the switching of each message. .in this connection, a key 9i is provided in the intraoiiice circuit and Operation thereof initiates the switching of all messages that may be in the tape i2 or which may appear therein between the time the key 9| is operated and the tape lever contacts 23 open. Operation of key el applies a ground through the coil of a relay 92 to potential whereby said relay is energized and locks up through its inner tongue and front contact. Operation of relay 92 applies ground from the tongue and back Contact of relay 3Q through tongues and back contacts of relays 2l and 38 to the fan circuit of relays i511, to ie and thence to the coils of one oi the pairs of line relays such as it and ita. The operation oi one of the pairs of line relays, such as it and la, the pair being selected by the directing character in the tap-e preceding the message, is effective in the manner described to initiate transmission oi the message through the intra-cnice circuit. the end-oi`message signal effects operation of relay 3s which removes ground from the holding circuit of the pair of operated line switching relays, such as le and ita, whereupon said relays release. The release of relay ita opens conductor No. tl oi cable 'Sie which causes the vacuum tube il to cease drawing plate current and thereby efi'ect release of relay le. Relay it in releasing in turn effects release of relay 82 which opens the circuit through the -coil of relay whereupon this relay also releases and the line selecting equipmentv oi the intra-oiiice circuit is restored to its normal condition, which normal condition includes the energization of relays 2l and 22. The release of relay 39 reapplies ground to the ian circuit of relays la to i556 which are operated in accordance with the directing character preceding the next message, whereupon the intra-oice circuit functions in the manner described to relay the' next message in the tape i2 therethrough. Relay 38 is a slow-to-release relay and therefore the circuit to the stepping magnet SM of the tape transmitter li will not be recompleted for a short interval of time which is sufficient to permit relay 39' t0 operate andv release between messages.

Thus as long as messages continue to appear inthe tape i2 they will automatically ybe switched to their proper sending position circuit as determined by the directing characters preceding each message. Ii messages received over the circuit cease for a period of timeY suicient to permit the tape l2 to become taut and open contacts 23, the circuit to the step magnet SM ci the tape transmitter it is interrupted through the left- At the end of the message,

10 hand coil of relay 23 whereupon said relay operates and through its left-hand tongue applies a ground through a back contact and tongue of relay 27 tothebatteried terminal `of relay E32. This causes relay t2 to releaseand if at this time a mes; sage is` being transmitted through the intra-o'ice circuit, -further switching Voi from the i2 through the circuit will be halted Awhen the relay 3:? operates at the end ci ,the message then in progress of being transmitted. if the tape lever contacts 2t open with blank tape -between t. e reperforator is and the transmitter ll,rsub sequent messages appearing in the tape will not be transmitted until either the keys 31 or 9| are operated.

k in order to prevent a message from being sent through the switching centerrto a line circuit, the remote oiiice or which is closed, each sending position circuit is provided with a close-out key iid. p The operation of the key 52 to open the contacts et thereof prevents the operating circuit to the sending positioncircuit seizing relay 56 from being completed; Hence, with relay 45t prevented irom oper-ating,v the sending position circuit associated with an operated close-outkey e2 cannot be connected toA an intra-cnice transmitter. K W y 11" an lintra-office transmitter selects a closed out sending position circuit and eiiects illumina'- tion of the connection requeStlamp 36, the operation of either key 3l or key si will cause operation of the proper line switching relays and the connection request lamp to be extinguished. ,Re-,-v lays and 'irwill operate but relays 8l and 5 6 will not, and therefore the transmitter ll will not start. Innsuch an event, the operator could note by oloservingthe close-out lamps such as 99, one of which is provided for each sending position circuit and` which is lighted When its associated sending circuit is closed out, whythe transmitterV failed to Start. Y

A message to a closed out oiiice may 'be sent at times to 'the nearest open office through the respective sending position circuit even though the directing character preceding the message has at'- ternpted t0 select a closed out sending position. In such an event, the nearest open oiiice is manually selected by the operation of a key individual to the sending position circuit associated with this open oiiice. These keys e3 to 9 6, oneAk foreach pair ci line switching relays,v surchhas l5 and IBa, permit any oneY pair of the lineIV switching relays to be' operated at a time. Operation of anyd one of the' keys,- 93 to Q'ii, completes alcircuitV from ground at the back contact and outerptongue of relay 38" through the coils of` its associated pair of line s witching'relays, such as Igand iSd., i

n Following the operation of a pair of line switch;- ing relaysv by the operation of a key, suchas 93, the transmission of the stored message is effected in the samernaner as described abovegwherethe selection' of a sending position circuit is p erformed automatically. It will beY noted that while a pair of line switching relays, such as iiand 16a, may be energized by the operationof its associated key, such as' 93, a locking circuit to such relays will not be' established unless all the otherI line'switchi'rlg' relays are deenergized. Lamps 91,

one associated with each pair of line switchingrelays, has the circuit completed thereto when the circuit is established to its associated line switching relays. Hence, the illumination of one of the lamps 9'! indicates to which sending position circuit an intra-office transmitter may be connected. f

When a perforator, such as i3, is controlled from a keyboard or other appropriate unit at the local sending position of a switching center, each message sent from the local position will have immediately following the directing character thereof the call letter or designating character of the switching ofjce. In the case of the circuit shown, Q is the oice call letter of the switching center. Should the local operator fail to insert the directing character at the beginning of the message, the local oice call letter will be the first character of a message to appear over the pins of the transmitter and as described will effect operation of relays la to le accordingly. When these relays are operated in accordance with the local office call letter, a circuit is completed from ground through the outer tongues thereof and the coil of relay 42 to potential, whereupon said relay is operated. The operation of this relay opens the described circuit which with switch 43 closed, normally effects the stepping of the message directing character out of the tape transmitter Il. Hence, with relay 42 operated, the call letter of the local office will not be advanced through the transmitter. Normally, the call letter of the local oiiice will not be the same as the directing character of a message and therefore with relays I5a to ic operated in response to the call letter the operation of either key 31 or 9| will not initiate the transmission of a message from the tape Il even though the connection request lamp 3S is illuminated. In such an event, the operator may determine the destination of the message and operate `the corresponding one of the keys 93 to 96 to initiate the transmission of the message to the proper sending position circuit. Since the first character of such a message Will not be stepped out of the transmitter, which character will be the call letter of the local station, it will be transmitted as the first character of the message.

It will be obvious that various modifications and changes in the system, shown in the drawings and described herein, may be made without departing from the spirit or essential attributes of the invention, and it is desired therefore, that only such limitations be placed thereon as are specifically set forth in the appended claims.

What is claimed is:

1. In a telegraph system, a storage medium wherein` signals representing telegraph messages are stored, a telegraph transmitter for transmitting signals stored in said medium, a plurality of telegraph transmitting circuits, switching apparatus for extending a transmitting path from said transmitter to any one of said transmitting circuits at a time, means controlled by message directing signals preceding' each message stored in said medium for controlling said switching apparatus, a manually operable switch associated with said transmitter and means operativeV with said switch in one position to control said switching apparatus to transmit said message directing signals to transmitting circuits along with messages and with said switch in another position to transmit messages only to said transmitting circuits.

. 2. In a telegraph system, a storage medium having signals representing telegraph messages stored therein, a telegraph transmitter for transmitting signals stored in said medium, a plurality of telegraph transmitting circuits, switching apparatus. for extending a transmitting path fromv said transmitter to any one of said transmitting circuits at a time, means controlled by message directing signals preceding each message stored ill) in said medium for Ycontrolling said switchingY apparatus and to select transmitting circuits in accordance with the directing signals preceding each message, a manually operable element, means operative on the vactuation of said element following the operation of said switching apparatus for initiating operation of said transmitter to transmit a message therefrom, and means including end-of-message signals terminating each message stored in said medium for'halting operation of said transmitter after the transmission of a message therefrom.

3. In a telegraph system, a storage medium having signals representing telegraph messages stored therein, a telegraph transmitter for transmitting signals stored in said medium, a plurality of telegraph transmitting circuits, switching apparatus for extending a transmitting path from said transmitter to any one of said transmitting circuits at a time, means controlled by message directing signals preceding each message stored in said medium for controlling said switching apparatus and to selectV transmitting circuits in accordance with the directing signals preceding each message,` a first manually operable element, means operative on the actuation of said element following the operation of said switching apparatus for initiating operation of said transmitter to transmit a message therefrom, a second manually operable element and means operative on the actuation of said element to condition said switching apparatus to successively extend a transmitting circuit from said transmitter to the transmitting circuits indicated by the directing signals stored in said medium ahead of the messages.

4. In a telegraph system, a storage medium having signals representing telegraph messages stored therein, a telegraph transmitter for transmitting signals stored in said medium, a plurality of telegraph transmitting circuits, switching apparatus for extending a' transmitting path from v ally operable element, and means operative in the actuation of said second element and including said switching apparatus to automatically transmit all the messages stored in said medium to the transmitting circuits indicated Vby the directing signals preceding each message stored in the medium.

5. In a telegraph message switching oiiice, a storing device for storing telegraph Vmessages in a storage medium, each message stored in said medium being preceded by message directing sigv nals and terminated by end-of-message signals, a telegraphV transmitter for transmitting the signals stored in said medium, a plurality of outgoing telegraph channels terminating at said oilce, switching apparatus for extending a transmission path from said transmitter to any one of said channels at a time, means toy condition said switching apparatus to automatically establish successive paths of transmission from said transmitter to said outgoing channels under the control of the message directing signals and effect auto-Y` matic transmission of said messagesY from said iiice, means to condition said switching apparatus to select only an outgoing channel in response to a directing signal preceding a message and means responsive to a manual operation to initiate the transmission of the accompanying message from said transmitter.l

6. In a telegraph switching system, a storage medium, a storing device for storing messages in said medium with each of the said messages preceded by directing signals and terminated by endof-message signals, a transmitter for transmitting signals representative of those stored in said medium, a plurality of outgoing telegraph channels, switching means for extending a transmission path from said transmitter to any one of said channels at a time, manually operable means to condition said switching means to atuomatically extend said transmission paths from said transmitter to said channels in accordance with said directing signal preceding said messages and in response to end-of-message signals to interrupt extended paths and condition said switching means to respond to following directing signals, and means to halt further automatic operation of said switching means following transmission of the next end-o-message signal after the amount of said storage medium between said storing device and said transmitter reaches a predetermined minimum.

'7. In a telegraph switching system, a storage medium, a storing device for storing messages in said medium with each of the said messages preceded by directing signals and terminated by end-of-message signals, a transmitter for transmitting signals representative of those stored in said medium, a plurality of outgoing telegraph channels, switching means for extending a transmission path from said transmitter to any one of said channels at a time, manually operable means to condition said switching means to automatically extend said transmission paths from said transmitter to said channels in accordance with said directing signal preceding said messages and in response to end-of-message signals to interrupt extended paths and condition said switching means to respond to following directing signals, means to halt further automatic operation of said switching means following transmission of the next end-of-message signal after the amount of said storage medium between said storing device and said transmitter reaches a predetermined minimum, and means to delete said message directing signals from the messages transmitted to said outgoing channels.

8. In a telegraph switching system, a storage medium, a storing device for storing messages in said medium with each of the said messages preceded by directing signals and terminated by end-of-message signals, a transmitter for transmitting signals representative of those stored in said medium, a plurality of outgoing telegraph channels, switching means for extending a transmission path from said transmitter to any one of said channels at a time, manually operable means to condition said switching means to automatically extend said transmission paths from said transmitter to said channels in accordance with said directing signal preceding said messages and in response to end-of-message signals to interrupt extended paths and condition said switching means to respond to following directing signals, means to halt further automatic operation of said switching means following transmission of the next end-of-message signal after the amount of said storage medium between said storing device and said transmitter reaches a predetermined minimum, a switch, means operative with said switch in one position to condition said switching means to delete said directing signals from the messages as they are transmitted to said outgoing channels and with said switch in another position to condition said switching means whereby said directing signals are transmitted along with the messages.

WILLIAM B. BLANTON. ROBERT C. AYERS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,346,173 Light Apr. 11, 1944 2,375,383 Potts May 8, 1945 2,381,871 Bacon Aug. 14, 1945 2,392,356 Bacon Jan. 8, 1946 

